Orthodontic bracket with rotary ligating cover

ABSTRACT

The present invention provides designs for a self-ligating orthodontic bracket. According to one embodiment, the self-ligating orthodontic bracket includes a mounting base for attachment to a tooth surface, an archwire slot formed upon the base and sized for receiving an orthodontic archwire, a rotary ligating cover selectively rotatable between an open position permitting access to the archwire slot and a closed position covering the archwire slot, and one or more locking features for holding the rotary ligating cover in a closed position. In one embodiment, the bracket includes one or more locking tabs on the rotary ligating cover aligned in coplanar relation to the rotary ligating cover and cooperatively mating with cutout portions in the base. In one embodiment, the bracket includes at least one resilient retention mechanism adjacent to the one or more locking tabs and aligned in coplanar relation to the rotary ligating cover. The resilient retention mechanism may include one or more relief channels permitting flexing of at least portions of the rotary ligating cover adjacent to the one or more locking tabs.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

BACKGROUND OF THE INVENTION

This disclosure relates to self-locking or ligatureless orthodonticbrackets. More particularly, this disclosure relates to self-ligatingorthodontic brackets each having a rotary ligating cover for retainingan archwire therein.

Orthodontic treatment generally comprises dental work to correctirregularities of the teeth or of the relation of the teeth tosurrounding anatomy. The irregularities may involve malocclusions withvarying degrees of severity. Class 1 malocclusions, for example, mayinvolve spacing irregularities such as excessive crowding or diastema (agap between two adjacent teeth). Class 2 malocclusions may involveoverbite conditions where the upper anterior teeth project labially overthe lower anterior teeth. Class 3 malocclusions, in contrast, mayinvolve underbite conditions where the upper anterior teeth close withinthe lingual side of the lower anterior teeth. For these and otherobserved irregularities, treatment typically involves installation ofbraces or mechanical aids for repositioning the teeth into correctorthodontic alignment.

Braces generally include orthodontic brackets configured for attachmentto the labial or lingual surfaces of the teeth or for attachment tometallic bands secured around the teeth. The brackets typically includearchwire slots within which a flexible yet resilient archwire may beengaged. Each bracket is typically bonded to the tooth surface so thatthe bracket's archwire slot is oriented for engagement with thearchwire. Various techniques are used for orienting the brackets. Forexample, an edgewise appliance comprises braces whereby each bracket isoriented and bonded to the tooth so that the archwire slot isperpendicular to the long axis of the root of the tooth. Alternatively,a straight-wire appliance includes braces whereby each bracket isoriented and bonded to the tooth so that the archwire slot is parallelto the occlusal plane (the plane of the biting surfaces of the teeth).

The archwire is typically a curved metallic wire having a rectangular orcircular cross section that is bent or twisted prior to engagement withthe brackets. The memory or restoring force exerted by the archwire uponthe brackets serves to move the teeth into the desired alignment.Throughout the duration of orthodontic treatment, the orthodontistperiodically adjusts the shape of the archwire (as well as theconfiguration of other attachments such as elastic bands and so forth)to achieve the correct orthodontic alignment.

Most brackets in current use incorporate tie wings or extensions thatproject upwardly and downwardly in a gingival-occlusal orientation andrequire the use of ligatures or ligating modules to hold the archwirewithin the archwire slots. The ligatures or ligating modules aretypically donut-shaped elastomeric rings or wires that are stretchedaround or twisted around the tie wings.

The use of such ligatures or ligating modules presents a number ofinherent disadvantages, some of which are mentioned herein. The smallsize of the ligatures or ligating modules requires substantial time forinstallation of the archwire. Because the orthodontist will typicallymake numerous adjustments to the archwire throughout orthodontictreatment, the orthodontist will likely remove and replace the ligaturesor ligating modules numerous times. Hygiene is another problem since theuse of ligatures or ligating modules increases the areas where foodparticles may be trapped. Further, with movement due to chewing or otheractivities, the ligatures or ligating modules may become detachedaltogether, allowing the archwire to disengage from the archwire slots.

Ligatures or ligating modules also present other limitations in terms ofthe forces exerted upon the brackets. For example, the labial or outwardforce that may be applied to a tooth having a bracket bonded to itslabial surface is limited to the strength of the ligature or ligatingmodule in the labial direction. On the same tooth, the force that may beapplied in the lingual direction is not so constrained (because theforce is applied against the bracket structure rather than the ligatureor ligation module).

Traditional bracket systems generally rely on active ligation usingelastomeric or wire ligatures wrapped about the tie wings of the bracketto hold the archwire into the archwire slot. The two areas that hold thearchwire most securely are the mesial and distal ends of the bracketwhere the elastomeric or wire ligatures make contact with the archwire,binding the archwire. This binding creates friction during orthodontictooth movement and consequently increases the forces needed for levelingand sliding tooth movement during treatment.

By contrast, passive self-ligating (or so-called frictionless) bracketsystems, or bracket systems that do not require traditional ligatures orligating modules, have been developed which rely on a principle thatforces employed to reposition teeth should not overwhelm the supportingperiodontium and facial musculature. Forces applied should instead beminimized to a level just large enough to stimulate cellular activityand, thus, tooth movement without unnecessarily disturbing the vascularsupply to the periodontium.

Several self-locking or self-ligating (ligatureless) orthodonticbrackets have been designed. However, most of those have complexdesigns, incorporating features requiring prohibitively expensivemachining operations or comprising multiple separate parts, which inturn increases the number of failure modes for such brackets. Otherdesigns have been rejected in the marketplace due to poor quality orpoor design, a lack of available features, difficulty of use, or otherfactors.

What is needed, therefore, is an orthodontic bracket that incorporates aself-ligating capability and that offers a different style of bracketthan those available today.

The foregoing and other objectives, features, and advantages of theinvention will be more readily understood upon consideration of thefollowing detailed description of the invention taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL DRAWINGS

For a more complete understanding of the present invention, the drawingsherein illustrate examples of the invention. The drawings, however, donot limit the scope of the invention. Similar references in the drawingsindicate similar elements.

FIG. 1 illustrates an isometric view of a self-ligating orthodonticbracket according to one embodiment of the invention.

FIG. 2 illustrates an exploded isometric view of a self-ligatingorthodontic bracket having a bracket base, rotary ligating cover, andretaining pin, according to one embodiment of the invention.

FIG. 3 illustrates an exemplary frontal view of a self-ligatingorthodontic bracket engaged with an archwire.

FIG. 4 illustrates a sectional view of a self-ligating orthodonticbracket with a rotary ligating cover in a closed position, according toone embodiment of the invention.

FIGS. 5A-5C illustrate sectional views of a rotary ligating cover upon abracket base in closed and partially open positions, according tovarious embodiments of the invention.

FIG. 6 illustrates a top view of a self-ligating orthodontic bracketwith a rotary ligating cover in a partially open position, according toone embodiment of the invention.

FIG. 7 illustrates a top view of a self-ligating orthodontic bracketwith a rotary ligating cover in an open position, exposing an archwireslot within a bracket base, according to one embodiment of theinvention.

FIG. 8 illustrates a top view of a rotary ligating cover according to analternate embodiment of the invention.

FIG. 9 illustrates a top view of a rotary ligating cover according toanother alternate embodiment of the invention.

FIG. 10 illustrates a sectional view of a self-ligating orthodonticbracket with a rotary ligating cover in a closed position, according toan alternate embodiment of the invention.

FIG. 11 illustrates a sectional view of a self-ligating orthodonticbracket with a rotary ligating cover in a closed position, according toanother alternate embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the presentinvention. However, those skilled in the art will understand that thepresent invention may be practiced without these specific details, thatthe present invention is not limited to the depicted embodiments, andthat the present invention may be practiced in a variety of alternateembodiments. In other instances, well known methods, procedures,components, and systems have not been described in detail.

Various operations will be described as multiple discrete stepsperformed in turn in a manner that is helpful for understanding thepresent invention. However, the order of description should not beconstrued as to imply that these operations are necessarily performed inthe order they are presented, nor even order dependent.

Turning now to the several drawings, FIG. 1 illustrates an isometricview of a self-ligating orthodontic bracket 100 according to oneembodiment of the invention. The self-ligating orthodontic bracket 100includes a mounting base 105 for attachment to a tooth surface, anarchwire slot 110 formed upon the mounting base 105 and sized forreceiving an orthodontic archwire (not shown), and a rotary ligatingcover 115 (shown in a closed position) for retaining an orthodonticarchwire within the archwire slot 110. As will be discussed in greaterdetail below, the rotary ligating cover 115, in one embodiment,comprises a plate (as shown) that may rotate about an axial member suchas a retaining pin 120 positioned in an eccentric manner, i.e., thepivot point positioned on one side of the bracket 100, and having apivot axis oriented perpendicular to the archwire slot 110 andsubstantially normal to the tooth surface and mounting base 105 bondedthereon. The rotary ligating cover 115 preferably includes one or morecoplanar resilient retention features (or locking mechanisms) 125 forholding the rotary ligating cover 115 in a closed position therebyretaining an orthodontic archwire within the archwire slot 110.

As shown in FIG. 1, the one or more coplanar resilient retentionfeatures 125 may comprise resilient portions of the rotary ligatingcover 115 suitably formed to allow coplanar deflection and subsequentlocking of one or more protruding surfaces of the rotary ligating cover115 with one or more corresponding indentations 130. Here, the resilientretention features 125 have been designed to deflect inward, toward theaxis of the retaining pin 120, for lockable engagement between one ormore protruding surfaces (or locking tabs) of the rotary ligating cover115 and one or more cooperatively mating indentations 130. In thisconfiguration, the resilient retention features 125 deflect and engagewith the mating indentations 130 in directions coplanar with the rotaryligating cover 115. Consequently, forces exerted normal to the rotaryligating cover 115 (i.e., forces in a labial-lingual direction) as mayarise due to movement of an archwire retained within the archwire slot110, are not likely to affect the retention of the archwire within thearchwire slot 110. Thus, the self-ligating orthodontic bracket 100 moresecurely retains an archwire than other bracket designs.

Also shown in FIG. 1, the self-ligating orthodontic bracket 100 mayinclude one or more orthodontic tool features such as an outer surfacefeature 145 of the rotary ligating cover 115. The outer surface feature145 may be a protruding ridge (as shown), a recessed groove (not shown),a circular recessed area, or any of a number of suitable shapes andconfigurations that may improve the ease of use of the bracket 100. Forinstance, an orthodontic tool such as an explorer or scaler may be usedwith the outer surface feature 145 to rotatably open or close the rotaryligating cover 115 to expose or cover, respectively, the archwire slot110. Likewise, pliers or another orthodontic tool may be used with theouter surface feature 145 (perhaps along with one side of the bracket100) to close the rotary ligating cover 115. Further, the outer surfacefeature 145, alone or in combination with the retaining pin 120 andother visual aspects of the bracket 100, preferably provides acenterline for the bracket 100 useful to aid the orthodontist in theplacement of the bracket 100 upon the patient's tooth.

The self-ligating orthodontic bracket 100 preferably includes roundededges and chamfered archwire slot ends 150 to improve comfort for thepatient wearing the orthodontic appliance. As shown and as will bedepicted in many of the illustrations herein, the rotary ligating cover115, the exterior pan head shape of the retaining pin 120, and otherfeatures which may define the outer surfaces of the bracket 100 oppositethe mounting base 105, preferably comprise smooth and rounded shapes toimprove patient comfort and minimize the overall side profile or outwarddimension of the bracket 100 from the bonding surface of the mountingbase 105. Preferably, the outer surfaces of the one or more indentations130 and the neighboring edges 160 therebetween are coplanar and flushwith the outer surfaces of the rotary ligating cover 115 and, inparticular, with the outer surfaces of the one or more resilientretention features 125 and the neighboring or adjacent outer surfacestherebetween.

FIG. 2 illustrates an exploded isometric view of a self-ligatingorthodontic bracket 200 having a bracket base 205, rotary ligating cover210, and retaining pin 215, according to one embodiment of theinvention. As shown, the rotary ligating cover 210 may be rotatablyfastened to the bracket base 205 using retaining pin 215 insertedthrough a hole 220 in the rotating cover 210 and journalled into acorresponding hole 225 in a tie wing 230 formed on one side of thearchwire slot 235. The outward surface 240 of the bracket 205, oppositethe tooth mounting surface 245 and upon which the rotary ligating cover210 may be rotated when fastened to the bracket 205, preferablyencompasses substantially all of the outward facing surface area of thetie wing 230, and an axis of rotation 250 of the rotary ligating cover210 extends through the outward surface 240. A coplanar portion 255 ofthe opposing tie wing 260 on the other side of the archwire slot 235receives the bottom surface of the rotary ligating cover 210 so that therotary ligating cover 210, when in a closed position, coverssubstantially the full length of the archwire slot 235.

As will be described in further detail, the outward surface 240preferably incorporates concentric circular recesses 265 and 270 forlimiting rotation of the rotary ligating cover 210 due to asymmetries ofthe bracket 200. For example, for brackets 200 having a rhomboid orparallelogram overall shape as viewed from the outward surface of thebracket looking toward the tooth mounting surface 245 (or a frontalview), the rotary ligating cover 210 need not be symmetrical about itscenterline, the centerline formed by the through hole 220 and (as shown)the outer surface feature 275. For such an asymmetrical rotary ligatingcover 210, circular recess 265 may be used in combination withengagement of locking tabs 280 with cooperatively mating cutout portionsor indentations 285 to establish a closed position for the rotaryligating cover 210 when the rotary ligating cover 210 is rotated in aclockwise direction about the axis of rotation 250 as viewed from theoutward surface of the bracket 200 looking toward the tooth mountingsurface 245. As will be shown in successive views, the rotary ligatingcover 210 may incorporate a protruding nub on its lower surface thattracks within the concentric circular recesses 265 and 270.

In the embodiment shown in FIG. 2, the rotary ligating cover 210 may beclosed to cover the archwire slot 235 by turning the rotary ligatingcover 210 in a clockwise direction until the looking tabs 280 engagewith the cooperatively mating indentations 285 formed upon the tie wing260 and the protruding nub (not shown) reaches the end of (or justbeyond the end of) the circular recess 265. The rotary ligating cover210 may be opened to expose the archwire slot 235 by turning the rotaryligating cover 210 in a counterclockwise direction whereby theprotruding nub moves first within the circular recess 265 and then thecircular recess 270 until the archwire slot 235 is fully exposed.

Next, FIG. 3 illustrates an exemplary frontal view of a self-ligatingorthodontic bracket 300 engaged with an archwire 310. The bracket 300may be mounted to the labial (front) surface of a tooth as part of atypical bracket system. Or, alternatively, the bracket 300 may bemounted on the lingual (back) of a tooth surface as part of a lingual or“hidden” bracket system. As will be discussed further, the frontalprofile of the bracket 300 may be designed for use on particular toothsurfaces. For example, the bracket 300 may be designed to have aparticular rhomboid or parallelogram profile for bonding to a particulartooth, such as one of the upper or lower centrals, laterals, cuspids,bicuspids, molars, and so on.

The archwire 310 may be retained within the self-ligating bracket 300 sothat the archwire 310 runs in a mesial-distal orientation, parallel tothe occlusal surface (the cutting or incisal edge) of a tooth. Otherorientations may be used with the bracket 300. However, this orientationis typical of a straight-wire (or Roth) appliance whereby crownangulation and crown inclination are engineered into the bracket 300thereby allowing use of an archwire that is “straight” or parallel tothe cutting edge of each tooth (when the teeth are positioned in correctorthodontic alignment). Crown angulation is generally the mesial-distalto gingival-occlusal orientation of the tooth and is affected by themesial-distal orientation of the archwire slot (or slot tip). Crowninclination is generally the labial-lingual to gingival-occlusalorientation of the tooth and is affected by the rotational orientationof the archwire slot (or slot torque) along the mesial-distal (orarchwire) axis.

The bracket 300 shown in FIG. 3 has an engineered slot tip 320, which isthe angular offset between the centerline 325 of the bracket 300 and aline perpendicular to a mesial-distal line that is parallel with thearchwire 310. In orthodontic practice, the bracket 300 may be bonded toa tooth surface so that the centerline 325 of the bracket 300 is alignedwith the gingival-occlusal axis (or long axis) of the tooth's clinicalcrown.

Whereas a straight-wire appliance typically includes individuallyengineered brackets with each bracket having the desired crowninclination (slot torque) and crown angulation (slot tip) for aparticular tooth, other techniques may be used which require differentorientations. For example, a standard edgewise appliance typicallyincludes brackets having a rectangular profile and an orientation suchthat the centerline of the bracket is aligned along thegingival-occlusal axis (or long axis) of the clinical crown andperpendicular with the archwire slot. Typically, the brackets in astandard edgewise appliance have archwire slots that are not parallel tothe incisal edges of the teeth (when the teeth are positioned in correctorthodontic alignment). Instead, the archwire is angled, bent, andtwisted to define the desired position of the teeth.

As commonly practiced in orthodontic treatment, brackets may befabricated for a particular patient by prescription. The brackets may beengineered to include the appropriate slot torque and slot tip for eachindividual tooth for the particular patient. For example, specificallyengineered brackets may be fabricated for the upper left central, theupper left lateral, the upper left cuspid, and so forth moving distallytoward the upper left molars (using Palmer's notation for designatingindividual teeth). Each bracket typically incorporates a particular slottorque and slot tip as well as other features as may be needed. Forinstance, the bracket for the upper left cuspid may include a slot tip320 of, perhaps, 9° and include a ball hook 330 for use with elastics orother features of the orthodontic appliance.

Still referring to FIG. 3, the mounting base 315 of the bracket 300 maybe sized to fit a particular tooth surface. For example, the mountingbase 315 may be wider at the incisal end of the tooth to match the shapeof the tooth surface. The bracket 300 may be bonded to the surface of atooth, or, alternatively, to a band assembly which is attached to thetooth. The bracket 300 is oriented so that the rotary ligating cover 335pivots about an axial member 340 positioned on the tie wing on the sideof the archwire slot closest to the incisal end of the tooth surface(and opposite the gingival end). However, the bracket may be oppositelyoriented so that the rotary ligating cover 335 pivots about an axialmember 340 positioned on the on the gingival side of the archwire slot.

For the particular bracket 300 shown in FIG. 3, the rotary ligatingcover 335 follows the overall rhomboid or parallelogram shape of thebracket 300 and is not symmetrical about its centerline 325. Aprotruding nub or rotation stop 345 may be formed upon the underside ofthe rotary ligating cover 335 designed to track within concentriccircular recesses 350 and 355 when the rotary ligating cover 335 pivotsabout the axial member 340. For example, as the rotary ligating cover335 is rotated in a counterclockwise direction from the closed positionshown, the rotation stop 345 slides into and follows the first circularrecess 350, and, with further rotation, follows freely within the secondcircular recess 355. Likewise, as the rotary ligating cover 335 isrotated in a clockwise (or closing) direction, the rotation stop 345follows freely within the second circular recess 355 and then followswithin the first circular recess 350 until sliding up to and slightlybeyond the end of the first circular recess 350.

As the rotary ligating cover 335 rotates in a clockwise direction aboutthe axial member 340, the resilient retention features (or mechanisms)360 deflect inward, toward the axial member 340 until locking tabs 365engage with cooperatively mating cutout portions (or indentations) 370.In the embodiment shown, the resilient retention features 360 resemblecoplanar fingers within the rotary ligating cover 335, whereby reliefchannels 375 permit flexing of at least portions of the resilientretention features 360 adjacent to the locking tabs 365.

As will be appreciated, in one embodiment the orientation of concentriccircular recesses 350 and 355, and associated rotation stop 345, may bereversed such that the rotary ligating cover 335 may be opened in aclockwise direction of rotation and closed in a counterclockwisedirection of rotation. Likewise, the positions of the locking tabs 365and corresponding indentations 370 may be reversed, according to oneembodiment, yet still provide the intended function. The bracket 300 mayinclude one or more locking tabs (such as locking tabs 365) aligned incoplanar relation to the rotary ligating cover 335 and cooperativelymating with cutout portions in the rotary ligating cover. In otherwords, the one or more locking tabs may be formed upon the bracket base,and the cooperatively mating cutout portions, to which the locking tabsengage when the ligating cover is in a closed position, may be formedupon the rotary ligating cover.

Next, FIG. 4 illustrates a sectional view (such as through centerline325 in FIG. 3) of a self-ligating orthodontic bracket 400 with a rotaryligating cover 405 in a closed position, according to one embodiment.The bracket 400 includes a mounting base 410 and a pair of tie wings 415and 420 formed thereon and extending outward, away from the mountingbase 410, and defining an archwire slot 425 therebetween. The archwireslot 425 is sized for receiving an orthodontic archwire 430, and therotary ligating cover 405 is selectively rotatable between a closedposition (as shown) for securably retaining the archwire 430 within thearchwire slot 425 and an open position (not shown) for permitting accessto the archwire slot 420. The rotary ligating cover 405 may rotate aboutan axial member such as a retaining pin 435 positioned on one side ofthe bracket 400 such as on one of the tie wings 420. The retaining pin435 shown incorporates a pan head extending over the outward surface ofthe rotary ligating cover 405 and a lower portion journalled orfastenably attached into a receiving hole or recess area in the tie wing420. As shown, the retaining pin 435 may be dimensioned with a smallerdiameter that is inserted into the receiving hole in the tie wing 420and a larger diameter about which the rotary ligating cover 405 mayslidably rotate. The smaller diameter, according to one embodiment,permits a press-fit operation for retaining the rotary ligating cover405 to the bracket 400 whereby the smaller diameter of the retaining pin(or dowel) 435 is forcibly pressed into the receiving hole in the tiewing 420. However, other configurations may be used. For example, aretaining pin having a single diameter may be used, perhaps withprecision fastening equipment to ensure that the retaining pin is ableto rotate freely about the retaining pin.

The pair of tie wings (as shown, 415 and 420) generally extendtransverse to the archwire slot 425 with one tie wing (i.e., 415)extending from the archwire slot 425 in a gingival direction and theother (i.e., 420) extending from the archwire slot 425 in an occlusaldirection. The tie wings 415 and 420 provide additional utility andflexibility for the orthodontist in applications where the use ofstandard elastomeric ligatures or other attachments requiring tie wingsmay be desired. The use of standard elastomeric ligatures createsfriction between the archwire and the elastomeric ligature. Thefriction, or active engagement, with the archwire 430 allows foradditional forces to be applied to a tooth surface 440 bonded to thebracket 400. For example, active engagement with the archwire 430 may beused to urge tooth movement along the mesial-distal (or archwire) axis(to increase or decrease spacing between adjacent teeth). Activeengagement with the archwire 430 may also be used to increase the forcesapplied to change crown angulation (affected by slot tip) and crowninclination (affected by slot torque).

In contrast, the self-ligating bracket 400 may rely on passiveengagement with the archwire 430. With passive engagement, the archwire430 is not forcibly restrained within the archwire slot 425 and isinstead allowed to move within the archwire slot 425. Such brackets maycomprise a passive or so-called frictionless bracket system and do notrequire traditional ligatures or ligating modules. In such systems, thearchwire 430 is free to slide within the archwire slot 425 along themesial-distal axis.

As previously discussed, crown inclination is generally thelabial-lingual to gingival-occlusal orientation of the tooth and isaffected by the rotational orientation of the archwire slot 430 alongthe mesial-distal axis. An axial (or sectional) view of the bracket 400along the mesial-distal axis is shown in FIG. 4. Here, the archwire slot425 is shown angled (or rotated) slightly such that the labial-lingualsides of the archwire slot 425 (which are normal to the rotary ligatingcover 405) are not perpendicular (or not normal) to the tooth surface440. This is a typical rotational orientation for the archwire slot usedin a straight-wire appliance where slot torque is engineered into thebracket. A standard edgewise appliance, in contrast, typically includesan archwire slot with sides perpendicular to the mounting surface of thetooth.

Turning now to FIGS. 5A-5C, sectional views are illustrated showing therotary ligating cover 335 upon a bracket base 315 (or a tie wing 500thereon) in closed and partially open positions, according to variousembodiments of the invention. FIG. 5A depicts the sectional viewindicated in FIG. 3 and shows the rotary ligating cover 335 in a closedposition with the rotation stop 345 slightly beyond the end of thecircular recess 350. The slight separation 505 between the rotaryligating cover 335 and the mating surface of the tie wing 500 mayprovide additional retention forces for holding the rotary ligatingcover 335 in a closed position. For example, the frictional forcesbetween the rotation stop 345 and the outward surface of the tie wing500 and the frictional forces involving the axial member (not shown)retaining the rotary ligating cover 335 may provide additional retentionforces beyond the retention forces provided by engagement of otherlocking features associated with the rotary ligating cover 335, such as,for example, coplanar locking tabs along the edge surface of theligating cover 335.

FIG. 5C depicts a sectional view as in FIG. 5A, according to oneembodiment, showing the rotary ligating cover 335 in a closed positionwith the rotation stop 345 formed upon the lower surface of the ligatingcover 335 and positioned outside of or beyond the end of the circularrecess 350. However, the rotation stop 345 is shown seated within acooperatively mating cutout portion of the outward surface of the tiewing 500 and, thereby, holding the rotary ligating cover 335 in a closedposition.

FIG. 5B depicts the sectional view with the rotary ligating cover 335 ina partially open position with the rotation stop 345 shown trackingwithin the circular recess 350. Here, the rotary ligating cover 335 hasbeen partially opened (in a counterclockwise direction) whereby therotation stop 345 has dropped into the circular recess 350.

As the rotary ligating cover 335 is opened further (still rotating in acounterclockwise direction), the rotation stop 345, in one embodiment,leaves the circular recess 350, as illustrated in FIG. 6. Also shown inFIG. 6 are the relative positions of locking tabs 365 and theircooperatively mating cutout portions (or indentations) 370, according toone embodiment. As the rotary ligating cover 335 opens, pivoting aboutthe axial member 340, the locking tabs 365 become unseated from theircorresponding indentations 370 allowing the rotary ligating cover 335 torotate more freely.

FIG. 7 illustrates a top view of a self-ligating orthodontic bracket,according to one embodiment, as in FIG. 6, except that the rotaryligating cover 335 is in an open position, exposing the archwire slot700 formed upon the bracket base 315. Here, the rotary ligating cover335 has been rotated in a counterclockwise direction until the archwireslot 700 is fully exposed. Through this portion of rotation, therotation stop 345 has tracked within the circular recess 355. In oneembodiment, the rotation stop 345 moves up against an end in thecircular recess 355 (not shown) for stopping the counterclockwiserotation of the rotary ligating cover 335 when the archwire slot 700becomes fully exposed.

As will be appreciated, variations of the self-ligating orthodonticbracket described herein may be apparent. For example, FIG. 8illustrates a top view of a rotary ligating cover 800 according to analternate embodiment of the invention. The rotary ligating cover 800incorporates relief areas 805 cut out behind the locking tabs 810leaving resilient retention features 815 that deflect inward, indirections coplanar with the rotary ligating cover and toward the axialmember 820 about which the rotary ligating cover is able to pivot. Forexample, as the rotary ligating cover 800 rotates into a closedposition, the resilient retention features 815 deflect inward indirections perpendicular with the pivot axis of the axial member 815,allowing the locking tabs 810 to engage with cooperatively mating cutout portions or indentations (not shown) in the bracket base.

FIG. 9 illustrates a top view of a rotary ligating cover 900 accordingto another alternate embodiment of the invention. The rotary ligatingcover 900 incorporates one or more locking tabs 905 which engage withcooperatively mating cutout portions or indentations (not shown) in thebracket base when the rotary ligating cover 900 is rotated into a closedposition. The one or more locking tabs 905 are preferably aligned incoplanar relation to rotary ligating cover 900 as shown, cooperativelymate with cutout portions in the bracket base (not shown), and arecapable of exerting retention forces in a direction coplanar with therotary ligating cover and, thereby, holding the rotary ligating cover ina closed position.

FIG. 10 illustrates a sectional view of a self-ligating orthodonticbracket 1000 (along its centerline as in FIG. 4) with a rotary ligatingcover 1005 in a closed position, according to an alternate embodiment ofthe invention. Similar with the bracket shown in FIG. 4, bracket 1000comprises a mounting base 1010 for mounting the bracket 1000 upon atooth surface 1040 and a pair of tie wings 1015 and 1020 formed upon themounting base 1010, extending outward therefrom and defining an archwireslot 1025 therebetween. The rotary ligating cover 1005 is rotatablyfastened upon one of the tie wings 1020 and is capable of rotatably andsecurely closing over the archwire slot 1025 and an archwire 1030therein. However, the rotary ligating cover 1005 may be rotatablyfastened using a retaining pin 1035 that fits into a bushing 1045 formedupon the tie wing 1020. The retaining pin 1035 may be any fastener witha pan head or similar head structure capable of retaining the rotaryligating cover 1005 by overlapping the outward surface of the bushing1045 and a portion of the outward surface of the rotary ligating cover1005 extending outward from the bushing 1045. In one embodiment, theretaining pin 1035 includes one or more axial ribs 1050 for improvinginterference fit and retention forces of the retaining pin 1035 withinthe bushing 1045 and hole or recess extending below the bushing 1045toward the bracket mounting base 1010.

FIG. 11 illustrates a sectional view of a self-ligating orthodonticbracket 1100 (along its centerline as in FIG. 4) with a rotary ligatingcover 1105 in a closed position, according to another alternateembodiment of the invention. Similar with the bracket shown in FIG. 4,bracket 1100 comprises a mounting base 1110 for mounting the bracket1100 upon a tooth surface 1140 and a pair of tie wings 1115 and 1120formed upon the mounting base 1110, extending outward therefrom anddefining an archwire slot 1125 therebetween. The rotary ligating cover1105 is rotatably fastened upon one of the tie wings 1120 and is capableof rotatably and securely closing over the archwire slot 1125 and anarchwire 1130 therein. However, the rotary ligating cover 1105 may berotatably fastened about a stud 1135 formed upon the tie wing 1120 andcoined (or mushroomed) to retain the rotary ligating cover 1105. FIG. 11shows the sectional view prior to the coining operation. During thecoining operation, some of the material comprising the stud 1135 isdisplaced inward, toward the bracket mounting base 1110, and radiallyoutward from the stud 1135 to overlap an annular portion 1145 of theoutward surface of the rotary ligating cover 1005 immediately adjacentto the stud 1135. To facilitate the coining operation and to improve therepeatability and consistency of the overlap of the annular portion 1145of the rotary ligating cover 1105, a recess such as a conical recess1150 may be formed upon the outward facing surface of the stud 1135 (asshown). Likewise, other scribe lines or recess areas may be included asmay be needed depending upon the particular coining process andmaterials chosen for the bracket 1100.

The self-ligating orthodontic bracket described herein may comprise anyof a wide variety of materials suitable for use in an orthodonticappliance. Such materials have commonly included plastics, ceramics,stainless steel, titanium, or other metal alloys. The bracket preferablycomprises a biocompatible material with corrosion resistive properties,and the bracket preferably comprises materials which may be formed intothe structures shown yet maintain suitable strength characteristics forretaining commonly used orthodontic archwires or other components of anorthodontic appliance.

Nickel may be the most common metal associated with contact dermatitisin orthodontics. Recent figures suggest that perhaps 10% of patients aresensitive to nickel. Nevertheless, nickel-containing metal alloys, suchas nickel-titanium and stainless steel, are widely used in orthodonticappliances. Nickel-titanium alloys may have nickel contents above 50%and may potentially release enough nickel in the oral environment toelicit manifestations of an allergic reaction. Stainless steel has amuch lower nickel content, perhaps around 8%, and, because the nickel isbound in a crystal lattice within stainless steel, the nickel may beless available to react. Consequently, stainless steel orthodonticcomponents may be less likely to cause nickel hypersensitivity.

However, because of the remaining uncertainty regarding a particularpatient's sensitivity to nickel, it may be desirable to providenickel-free orthodontic brackets to avoid nickel hypersensitivityaltogether. Therefore, the self-ligating orthodontic bracket describedherein preferably comprises a nickel-free material. In one embodiment,the bracket comprises a nickel-free cobalt-chromium alloy.

Several methods may be used to manufacture the self-ligating orthodonticbracket described herein. For example, the bracket may be cast,machined, injection molded and so on. Injection molding of plastics maybe used as may be ceramic injection molding (CIM) or metal injectionmolding (MIM) depending upon the materials chosen. The bracket maycomprise a molded base coupled with a molded rotary ligating cover thatis coined to hold the cover to the bracket, or the bracket may comprisea molded base coupled with a molded ligating cover fastened to thebracket using a separate axial member press-fit onto the bracket. Forinstance, the bracket may comprise the assembly of a formed bracket bodyand a formed rotary ligating cover, the rotary ligating cover retainedupon a tie wing of the bracket body following a coining operationwhereby a stud protruding from the bracket body is mushroomed or coinedto retain the rotary ligating cover thereon. A ball hook, or othercomponents, may be welded to the bracket assembly or formed as part ofthe bracket body (i.e., as part of the molded bracket body).

The terms and expressions which have been employed in the forgoingspecification are used therein as terms of description and not oflimitation, and there is no intention in the use of such terms andexpressions of excluding equivalence of the features shown and describedor portions thereof, it being recognized that the scope of the inventionis defined and limited only by the claims which follow.

1. A self-ligating orthodontic bracket having: a mounting base forattachment to a tooth surface; an archwire slot formed upon said baseand sized for receiving an orthodontic archwire; a rotary ligating coverselectively rotatable between an open position permitting access to saidarchwire slot and a closed position covering said archwire slot; and oneor more locking mechanisms comprising cooperatively engaging featureslocated on said cover and said base for holding said rotary ligatingcover in a closed position.
 2. The bracket of claim 1, furthercomprising a pair of tie wings extending from said base and definingsaid archwire slot between said tie wings.
 3. The bracket of claim 2,wherein said one or more locking features comprise one or morerotational stops formed upon one of a lower surface of said rotaryligating cover and an outward surface of said base, said one or morerotational stops cooperatively mating with cutout portions in the otherof said lower surface of said rotary ligating cover and said outwardsurface of said base.
 4. The bracket of claim 1, wherein said one ormore locking features comprise one or more locking tabs formed upon oneof said rotary ligating cover and said base, said one or more lockingtabs aligned in coplanar relation to said rotary ligating cover andcooperatively mating with cutout portions in the other of said rotaryligating cover and said base.
 5. The bracket of claim 4, furthercomprising at least one resilient retention mechanism adjacent to saidone or more locking tabs and aligned in coplanar relation to said rotaryligating cover, said at least one resilient retention mechanism capableof exerting retention forces in a direction coplanar with said rotaryligating cover.
 6. The bracket of claim 5, wherein said at least oneresilient retention mechanism includes one or more relief channelspermitting flexing of at least portions of said resilient retentionmechanism adjacent to said one or more locking tabs.
 7. The bracket ofclaim 1, wherein said rotary ligating cover comprises a plateeccentrically rotatably mounted on an axial member journalled into saidbase.
 8. The bracket of claim 7, further comprising a pair of tie wingsextending from said base and defining said archwire slot between saidtie wings, said axial member journalled into a first one of said tiewings, said plate rotatably closable over said archwire slot andcooperatively mating with outward surfaces in a second one of said tiewings.
 9. The bracket of claim 7, wherein said one or more lockingfeatures comprise one or more rotational stops formed upon one of alower surface of said plate and an outward surface of said base, saidone or more rotational stops cooperatively mating with cutout portionsin the other of said lower surface of said plate and said outwardsurface of said base.
 10. The bracket of claim 9, further comprising oneor more concentric circular recesses formed upon one of said lowersurface of said plate and said outward surface of said base within whichsaid one or more rotational stops track when said plate is rotated, saidone or more concentric circular recesses defining an opening directionand a closing direction of said plate.
 11. The bracket of claim 7,wherein said one or more locking features comprise one or more lockingtabs formed upon one of said plate and said base, said one or morelocking tabs aligned in coplanar relation to said plate andcooperatively mating with cutout portions in the other of said plate andsaid base.
 12. The bracket of claim 11, further comprising at least oneresilient retention mechanism adjacent to said one or more locking tabsand aligned in coplanar relation to said plate, said at least oneresilient retention mechanism capable of exerting retention forces in adirection coplanar with said plate.
 13. The bracket of claim 12, whereinsaid at least one resilient retention mechanism includes one or morerelief channels permitting flexing of at least portions of said plateadjacent to said one or more locking tabs.
 14. The bracket of claim 7,wherein said axial member comprises a retaining pin for rotatablyfastening said plate to a hole in said base sized for receiving saidretaining pin.
 15. The bracket of claim 7, wherein said axial membercomprises a retaining pin for rotatably fastening said plate to a holewithin a bushing formed upon said base, said hole sized for receivingsaid retaining pin.
 16. The bracket of claim 7, wherein said axialmember comprises a stud formed upon said base and coined to rotatablyfasten said plate to said base.
 17. The bracket of claim 1, wherein saidone or more locking features comprise one or more rotational stopsformed upon one of a lower surface of said rotary ligating cover and anoutward surface of said base, said one or more rotational stopscooperatively mating with cutout portions in the other of said lowersurface of said rotary ligating cover and said outward surface of saidbase
 18. The bracket of claim 17, further comprising one or moreconcentric circular recesses formed upon one of said lower surface ofsaid rotary ligating cover and said outward surface of said base withinwhich said one or more rotational stops track when said rotary ligatingcover is rotated, said one or more concentric circular recesses definingan opening direction and a closing direction of said rotary ligatingcover.
 19. The bracket of claim 1, wherein said rotary ligating coverincludes one or more surface features for rotatably manipulating saidrotary ligating cover from a closed position to an open position or froman open position to a closed position using an orthodontic tool.
 20. Thebracket of claim 1, wherein features of said bracket define a centerlinetransverse to said archwire slot and useful as a visual aid forpositioning said bracket on said tooth surface.
 21. The bracket of claim1, wherein said bracket comprises a biocompatible material.
 22. Thebracket of claim 1, wherein said bracket comprises a cobalt chromiumalloy.
 23. The bracket of claim 1, wherein said bracket comprises aninjection molded bracket body.
 24. A self-ligating orthodontic brackethaving: a mounting base for attachment to a tooth surface; an archwireslot formed upon said base and sized for receiving an orthodonticarchwire; a pair of tie wings extending from said base and defining saidarchwire between said tie wings; and a rotary ligating cover selectivelyrotatable between an open position permitting access to said archwireslot and a closed position covering said archwire slot.
 25. The bracketof claim 24, further comprising one or more locking features adjacentsaid archwire slot for holding said rotary ligating cover in a closedposition, wherein said one or more locking features comprise one or morerotational stops formed upon one of a lower surface of said rotaryligating cover and an outward surface of a first one of said tie wings,said one or more rotational stops cooperatively mating with cutoutportions in the other of said lower surface of said rotary ligatingcover and said outward surface of said first one of said tie wings. 26.The bracket of claim 24, further comprising one or more locking featuresadjacent said archwire slot for holding said rotary ligating cover in aclosed position, wherein said one or more locking features comprise oneor more locking tabs formed upon one of said rotary ligating cover andsaid base, said one or more locking tabs aligned in coplanar relation tosaid rotary ligating cover and cooperatively mating with cutout portionsin the other of said rotary ligating cover and said base.
 27. Thebracket of claim 26, further comprising at least one resilient retentionmechanism adjacent to said one or more locking tabs and aligned incoplanar relation to said rotary ligating cover, said at least oneresilient retention mechanism capable of exerting retention forces in adirection coplanar with said rotary ligating cover.
 28. The bracket ofclaim 27, wherein said at least one resilient retention mechanismincludes one or more relief channels permitting flexing of at leastportions of said resilient retention mechanism adjacent to said one ormore locking tabs.
 29. The bracket of claim 24, wherein said rotaryligating cover comprises a plate eccentrically rotatably mounted on anaxial member journalled into a first one of said tie wings, said platerotatably closable over said archwire slot and cooperatively mating withoutward surfaces in a second one of said tie wings.
 30. The bracket ofclaim 29, further comprising one or more locking features adjacent saidarchwire slot for holding said rotary ligating cover in a closedposition, wherein said one or more locking features comprise one or morerotational stops formed upon one of a lower surface of said plate and anoutward surface of said first one of said tie wings, said one or morerotational stops cooperatively mating with cutout portions in the otherof said lower surface of said plate and said outward surface of saidfirst one of said tie wings.
 31. The bracket of claim 30, furthercomprising one or more concentric circular recesses formed upon one ofsaid lower surface of said plate and said outward surface of said firstone of said tie wings within which said one or more rotational stopstrack when said plate is rotated, said one or more concentric circularrecesses defining an opening direction and a closing direction of saidplate.
 32. The bracket of claim 29, further comprising one or morelocking features adjacent said archwire slot for holding said plate in aclosed position, wherein said one or more locking features comprise oneor more locking tabs formed upon one of said plate and said base, saidone or more locking tabs aligned in coplanar relation to said plate andcooperatively mating with cutout portions in the other of said plate andsaid base.
 33. The bracket of claim 32, further comprising at least oneresilient retention mechanism adjacent to said one or more locking tabsand aligned in coplanar relation to said plate, said at least oneresilient retention mechanism capable of exerting retention forces in adirection coplanar with said plate.
 34. The bracket of claim 33, whereinsaid at least one resilient retention mechanism includes one or morerelief channels permitting flexing of at least portions of said plateadjacent to said one or more locking tabs.
 35. The bracket of claim 29,wherein said axial member comprises a retaining pin for rotatablyfastening said plate to a hole in said first one of said tie wings sizedfor receiving said retaining pin.
 36. The bracket of claim 29, whereinsaid axial member comprises a retaining pin for rotatably fastening saidplate to a hole within a bushing formed upon said first one of said tiewings, said hole sized for receiving said retaining pin.
 37. The bracketof claim 29, wherein said axial member comprises a stud formed upon saidfirst one of said tie wings and coined to rotatably fasten said plate tosaid first one of said tie wings.
 38. The bracket of claim 24, furthercomprising one or more locking features adjacent said archwire slot forholding said rotary ligating cover in a closed position, wherein saidone or more locking features comprise one or more rotational stopsformed upon one of a lower surface of said rotary ligating cover and anoutward surface of a first one of said tie wings, said one or morerotational stops cooperatively mating with cutout portions in the otherof said lower surface of said rotary ligating cover and said outwardsurface of said first one of said tie wings.
 39. The bracket of claim38, further comprising one or more concentric circular recesses formedupon one of said lower surface of said rotary ligating cover and saidoutward surface of said first one of said tie wings within which saidone or more rotational stops track when said rotary ligating cover isrotated, said one or more concentric circular recesses defining anopening direction and a closing direction of said rotary ligating cover.40. The bracket of claim 24, wherein said rotary ligating cover includesone or more surface features for rotatably manipulating said rotaryligating cover from a closed position to an open position or from anopen position to a closed position using an orthodontic tool.
 41. Thebracket of claim 24, wherein features of said bracket define acenterline transverse to said archwire slot and useful as a visual aidfor positioning said bracket on said tooth surface.
 42. The bracket ofclaim 24, wherein said bracket comprises a biocompatible material. 43.The bracket of claim 24, wherein said bracket comprises a cobaltchromium alloy.
 44. The bracket of claim 24, wherein said bracketcomprises an injection molded bracket body.
 45. A self-ligatingorthodontic bracket having: a mounting base for attachment to a toothsurface; an archwire slot formed upon said base and sized for receivingan orthodontic archwire; a rotary ligating cover selectively rotatablebetween an open position permitting access to said archwire slot and aclosed position covering said archwire slot; and one or more lockingfeatures adjacent said archwire slot for holding said rotary ligatingcover in a closed position, wherein said one or more locking featurescomprise one or more locking tabs formed upon one of said rotaryligating cover and said base, said one or more locking tabs aligned incoplanar relation to said rotary ligating cover and cooperatively matingwith cutout portions in the other of said rotary ligating cover and saidbase.
 46. The bracket of claim 45, further comprising a pair of tiewings extending from said base and defining said archwire slot betweensaid tie wings.
 47. The bracket of claim 45, further comprising at leastone resilient retention mechanism adjacent to said one or more lockingtabs and aligned in coplanar relation to said rotary ligating cover,said at least one resilient retention mechanism capable of exertingretention forces in a direction coplanar with said rotary ligatingcover.
 48. The bracket of claim 47, wherein said at least one resilientretention mechanism includes one or more relief channels permittingflexing of at least portions of said resilient retention mechanismadjacent to said one or more locking tabs.
 49. The bracket of claim 45,wherein said rotary ligating cover comprises a plate eccentricallyrotatably mounted on an axial member journalled into said base.
 50. Thebracket of claim 49, further comprising a pair of tie wings extendingfrom said base and defining said archwire slot between said tie wings,said axial member journalled into a first one of said tie wings, saidplate rotatably closable over said archwire slot and cooperativelymating with outward surfaces in a second one of said tie wings.
 51. Thebracket of claim 49, further comprising one or more concentric circularrecesses formed upon one of said lower surface of said plate and saidoutward surface of said base within which one or more rotational stopstrack when said plate is rotated, said one or more concentric circularrecesses defining an opening direction and a closing direction of saidplate.
 52. The bracket of claim 49, wherein said axial member comprisesa retaining pin for rotatably fastening said plate to a hole in saidbase sized for receiving said retaining pin.
 53. The bracket of claim49, wherein said axial member comprises a retaining pin for rotatablyfastening said plate to a hole within a bushing formed upon said base,said hole sized for receiving said retaining pin.
 54. The bracket ofclaim 49, wherein said axial member comprises a stud formed upon saidbase and coined to rotatably fasten said plate to said base.